Help with caps / identifying Alcoa rims??

[99F350Michael]

I just purchased a '99 F350 with the rims that are in the picture. The Ford factory covers will not attach to the nuts that are on there....probably why when I got the truck home 2 of them were missing. Notice on the bottom right of the picture the nut 'washer' is in the wheel further compared to a few others??

I believe that these are Alcoa rims. They are in need of a good cleaning and it took me 2 hours just to do 1/2 of the rim.

1. What nuts will work with these rims to allow me to use the factory covers?

2. I have seen the Southwest Wheel Co. website and the Alcoa covers that they have. If the factory covers do not work with this setup, are their prices the best around?

Any advice/input would be appreciated.